if ( kettleFull() ) combi += 1;
if ( makingTea() ) combi += 2;
if ( makingCoffee() ) combi += 4;
switch ( combi )
   {
   case 0:
   case 1:
      break;
   case 2:
      addWater();
      boilWater();
      addTea();
      break;
   case 3:
      boilWater();
      addTea();
      break;
   case 4:
      addWater();
      boilWater();
      addCoffee();
      break;
   case 5:
      boilWater();
      addCoffee();
      break;
   case 6:
      addWater();
      boilWater();
      addCoffee();
      addTea();
      break;
   case 7:
      boilWater();
      addCoffee();
      addTea();
      break;
   }